In laser processing machines, it is typically necessary to measure a laser beam—ideally online, that is to say, during the laser processing operation—in terms of its properties such as power, beam position and beam diameter and/or intensity distribution. To this end, commercially available measuring devices already exist but they are often only suitable for use in a laboratory owing to their price and low level of robustness. In such a measuring device, for example, a small rapidly moved needle is commonly used in order to decouple a small portion of the laser radiation and redirect it to a rapid infrared detector. This needle can experience wear during extended use. Therefore such a measuring device typically has only limited suitability for long-term use in laser processing machines.
An alternative method for measuring the intensity profile of a laser beam uses a partially transparent redirecting mirror in the beam path of the laser beam in order to decouple a small portion of the beam power which substantially corresponds to the losses of the mirror, to a high-sensitivity resolution detector.